This invention relates generally to the field of two wheel vehicles. More specifically, the invention relates to two wheeled vehicle suspension systems and releasable wheel clamping systems.
The use of front and full suspensions in two wheeled vehicles has become widespread. For example, motorcycles have long had suspension systems. In recent years, front and full suspension systems in mountain bikes have become almost standard equipment. One pioneering effort to create such suspension systems was spearheaded by Rockshox, Inc. as described generally in U.S. Pat. Nos. 4,971,344; 5,186,481; 5,456,480; and 5,580,075, the complete disclosures of which are herein incorporated by reference. Another successful suspension system for a two wheeled vehicle is described in copending U.S. Applications Ser. Nos. 09/502,272 and 09/502,746, both filed Feb. 11, 2000, the complete disclosures of which are herein incorporated by reference.
This invention provides another type of suspension for two wheeled vehicles. The invention also relates to the releasable coupling of a wheel to the fork of a two wheeled vehicle.
In one embodiment, the invention provides a telescoping fork for the front wheel of a two wheeled vehicle. The fork comprises a pair of outer tubes that each have a top end and a bottom end. An upper structural member and a lower structural member are employed to connect the outer tubes, with the lower structural member being spaced below the upper structural member. Further, each outer tube tapers outwardly, both externally and internally, in a direction both from the top end and the bottom end toward the lower structural member. With such a configuration, the strength of the outer tubes is increased without significantly increasing the weight of the fork.
In one aspect, the lower structural member is welded to the outer tubes, and steering bearings are coupled between the upper structural member and the lower structural member. With this configuration, the steering bearings may be used to attach the fork to a vehicle frame. In another aspect, the lower structural member may have a hollow box sectional shape.
In one particular arrangement, the fork further includes a pair of inner tubes that are disposed to slide within the pair of outer tubes. The inner tubes each have a bottom end and a top end, and the bottom ends of the inner tubes extend out of the bottom ends of the outer tubes. In one option, a single bushing may be disposed between each outer tube and each inner tube. The bushings may be located at the bottom ends of the outer tubes and have a length that is longer than a diameter of the inner tube. The use of such a bushing helps maintain an oil layer between the bushing and the inner tube.
In another particular aspect, the fork may include a bracket disposed at the bottom end of each inner tube. The brackets are employed to clamp a front wheel axle to the inner tubes. Optionally, at least one of the brackets may have a mount for receiving a disk brake caliper.
Another feature of the fork is the use of a handle bar clamping device that is coupled to the upper structural member. In this way, a handle bar may be coupled to the fork.
One particular embodiment of the invention is an adjustable fluid damping system. The fluid damping system may comprise a damper tube extending upward from the top end of the inner tube (and in some cases the damper tube may simply be an extension of the inner tube), a hollow damper rod coupled to the top end of the outer tube and extending into the damper tube, and a damper piston valve coupled to the damper rod that seals against the damper tube. The fluid clamping system may further include a lock tube that is disposed within the damper rod. The damper rod may have at least one upper orifice and one lower orifice, and the lock tube may be rotatable from the top end of the outer tube to close the lower orifice to limit the amount of extension of the lower tube out of the upper tube. In this way, the amount of extension of the suspension system may easily be adjusted from outside of the fluid damping system. For instance, when ready to climb a steep hill, the rider may quickly adjust the lock tube by turning a knob to limit the amount of extension during climbing.
In one particular aspect, this is accomplished by configuring the damper piston valve as a one-way valve that permits fluid flow in an upward direction upon compression of the inner tube into the outer tube. Further, a sleeve may be disposed over a top portion of the damper rod and the lock tube. The sleeve is configured to close the upper orifice as the upper tube extends relative to the lower tube, such that further extension is prevented if the lower orifice is closed by the lock tube. Conveniently, a stop may be positioned between the top of the outer tube and the top of the inner tube to stop compression of the inner tube into the outer tube.
In one alternative aspect, the inner tube may have a closed end or section, and a sealed piston may be disposed inside the inner tube. The piston may be connected to a rod that extends and attaches to the top end of the outer tube. Further, a gas may be held within the inner tube and is compressed by the piston to provide a damping effect. Optionally, a spring may be disposed between the bottom end of the inner tube and the piston to form a biasing effect. The rod may also be hollow to permit the gas pressure in the inner tube to be adjusted by a valve at the top end of the outer tube.
In a further embodiment, the invention provides a releasable clamp system for clamping a wheel axle of wheel to a two-wheeled vehicle. The clamp system comprises a frame member that defines a shape that is configured to receive a portion of the wheel axle. A cover plate is privotally attached to the frame member and is configured to receive another portion of the wheel axle. In this way, the cover plate may be moved to a closed position where the frame member and the cover plate generally encompass and clamp the wheel axle, and to an open position where the wheel axle may be removed. A lever is pivotally attached to the cover plate, and a hook member is pivotally attached to the lever. The hook member is configured to hook onto the frame member and be pulled by the lever to secure the cover plate to the frame member when the cover plate is moved to the closed position.
In one aspect, the cover plate may be pivotally attached to a top end of the frame member to permit the wheel axle to be vertically released from the frame member. In another aspect, the inner surfaces of the frame member and the cover plate that are adjacent the wheel axle are each semi-circular in geometry.
In a further aspect, the hook member may be T-shaped, and the frame member may include a shoulder with a slot into which the hook member is received. Optionally, the hook member may be constructed of two pieces that are threadably connected together. In this way, the clamping force on the wheel axle may be adjusted by rotating the pieces relative to each other prior to clamping.
In yet another aspect, torsion springs may be provided at pivot points located where the cover plate attaches to the frame member and where the lever attaches to the cover plate. The torsion springs hold the cover plate open when not clamping the wheel axle. Further, a mount may be provided on the frame member to mount a disk brake caliper to the frame member.